Database Record Structure Dania Bilal IS 530 Fall 2007 Definition A database is a collection of information organized in a way that a computer program can quickly retrieve desired pieces of data Database Components Fields Records Files Database Fields Pieces of information a user can access Author Title Journal name Abstract Descriptors Other Fields Attributes Numeric e g accession number Textual e g author name Data Structure A scheme for organizing related pieces of information Basic types of data structures Files Records Trees Tables Files File A collection of records In Dialog a file also refers to a specific database Every file database has a number and or a name ERIC is a database with a file no 1 in Dialog Records Record A collection of fields which constitutes a complete set of information Author title journal name abstract etc A collection of records constitutes a file Trees Data is organized in a hierarchical structure Each element is attached to one or more elements that is directly beneath it Connections between elements branches Elements at bottom of a tree with no elements below them leaves Example Yahoo directory Tables Data is organized in rows and columns Example Excel spreadsheet Relational database management systems store data in the form of related tables Aleph system is based on a relational database management system called Oracle Dialog Database Documents or surrogates are stored in a linear file Linear file is transformed into an inverted file Dialog Database Structure Linear file Composed of document surrogates stored in the IR system in their full original form Inverted file Composed of all words included in document surrogates excluding stop words Linear File Documents have to be searched in their entirety to locate specific information needed Audiocassette is an analogy to a linear structure Slow and inefficient Inverted File Words in all documents can be searched instead of the whole text of the documents themselves Music CD is an analogy to an inverted structure Faster and more efficient Dialog Inverted File A list of words in each document surrogate is made Each word is numbered including phrases and excluding stop words the a an etc Words that are numbered are alphabetized numbers precede letters Dialog Inverted File Alphabetized entries are followed by the document number the field it is from e g AB DE and the number of the entry in that field Linear File Example 101 The origins of Don Giovanni Discusses the history and sources Mozart used in his opera Don Giovanni DE Mozart Opera Historical Analysis Inverted File Origins 101 Ti 2 Don 101 Ti 4 Giovanni 101 Ti 5 Discusses 101 Ab 1 History 101 Ab 3 Sources 101 Ab 5 101 Ab Ab 7 Mozart Used 101 6 Inverted File Mozart 101 DE 1 Opera 101 DE 2 Historical 101 DE 3 Analysis 101 DE 4 101 DE Historical Analysis 3 4 Indexing Words keywords Every important word in a document is indexed Example Information systems Indexed as 2 separate words and as a phrase Information word Systems word Information systems phrase Indexing Exercise Index a paragraph from Dr Bilal s Web page under research and publications Extract the keywords from the first line of the paragraph Indicate the position of each word and the field it appears in Demos Demo of a Dialog Record structure Demo of an Ebsco database record structure Demo of a Web page record structure html markup language and or other languages Demo of a record structure in Aleph